Repetitive plasma discharges in saline solutions

We describe some observations of plasma formation in aqueous electrolyte solutions (containing either sodium chloride or barium chloride), using a small planar electrode configuration driven by a repetitive bipolar voltage source. Plasma pulses of a few microseconds duration were established by a 100 kHz square wave of a few hundred volts peak to peak, drawing a current during the plasma period of several hundred milliamperes. Spectral measurements show the presence of strong ion lines, confirming that plasma is formed in the liquid. The process produces chemical radicals such as OH and, when placed in proximity to biological tissue, causes biological material volumetric removal, opening possibilities for new kinds of plasma-driven electrosurgery such as tissue debulking or cutting. (C) 2001 American Institute of Physics.